LONGITUDINAL FIBRES OF THE PEDAL SYSTEM. 



629 



the capsule, their relative positions are not constant, but vary somewhat. To 

 this point, however, we shall return when we come to speak of the function 

 of this tract. 



FIG. 146. 



fc 



lud 



Outline of a Transverse Dorso-ventral Section of the Right Half of the Brain. Natural size. 

 (Sherrington.) The section, which is taken at the level of the knee of the capsule, and is therefore 

 intermediate between those shown in Figs. 139 and 140, is introduced to illustrate the course of the 

 constituents of the pyramidal tract. OT, optic thalamus; Nc, nucleus caudatus the head only 

 appears in this section ; Pt, putamen ; Gp", Gp,' the two parts of the globus pallidus of the nucleus 

 lenticularis; C, the claustrum ; CE, the external capsule ; In, the island of Reil ; ca, the anterior 

 commissure, shaded to render it distinct and the fibres from the temporo-sphenoidal lobe which 

 pass into it being indicated by broken lines ; Op, the optic tract ; I v d, the end of the descending 

 horn of the lateral ventricle ; F, the fornix ; F', the end of the anterior pillar of the fornix in the 

 base of the thalamus ; cc, corpus callosum ; OP, anterior part of the occipital lobe, fc is the central 

 fissure, or fissure of Rolando. The course of the fibres of the pyramidal tract connected respectively 

 with the trunk, leg, and arm and hence with spinal nerves, and of those connected with the face 

 and hence with cranial nerves, is shown by broken lines. These are all seen converging into the 

 internal capsule, CI. This figure should in respect to the course of these fibres be compared with 

 the horizontal section shown in Fig. 144, and the sagittal figure shown in Fig. 145. S indicates the 

 course of the most anterior and dorsal part of the lemporo-occipital tract. The fine dotted lines 

 converging to the corpus callosum, c c, indicate the course of the callosal fibres. 



In the cms these fibres run exclusively in the pes and form a compact 

 strand (Fig. 137, Py) occupying the central and larger portion of the pes 

 between a small median portion on the inside and a lateral portion on the 



